E-Flite Ultra Micro 4-Site

I used to read about these indoor flying sessions they have in other parts of the country. You can see them on youtube, too -- people doing amazing aerobatics in huge cavernous double-size gyms or aircraft hangars. For a short time we actually had an indoor flying group in Milpitas, in a tiny middle school half-sized gym. It was fun though it was hard to fly most planes in a room that size, and it was so popular that the airspace was always packed. Alas, the school decided to stop renting out their gym so for years there was no place to fly indoors.

And then BAM started -- Bay Area Micros, run via BayRC.com, and now the south bay has place for indoor flying. Currently they're meeting every Friday (though this may turn out to be too often for most people) at the gym at the Sunnyvale community center.

And a lot has changed since those Milpitas crash-n-bash sessions. The new generation of micro electronics has made it possible to design planes well under an ounce -- like the 15-gram Parkzone Vapor -- as well as heavier, more aerobatic planes weighing one or two ounces.

After flying Dave's Vapor for a few sessions, I wanted something more aerobatic. Some of the advanced pilots were doing great indoor aerobatics with their Parkzone Mustangs and Sukhois, but those planes are rather fast, and most pilots seemed to spend their time smashing the warbirds into walls, the floor and each other before they could get in many loops or rolls.

And then Kasra showed up one night with an E-flite Ultra Micro 4-Site. I was in love -- it's tiny, it's an aerobatic biplane, it comes pre-built (I like flying but hate building) -- it's perfect!

Except -- maybe not so perfect. The 4-Site turned out to be a wicked flyer, touchy and unstable, with a tendency to flop out instead of flying stably. Darn! maybe I didn't want one after all.

So I waited, and eventually Kasra and Zak figured out the secret. Turns out all it needs is some flap mixing. You set up the radio so that when the elevator goes up, the flaps go down, and vice versa. Dave flew a 4-Site set up that way, and assured me that I'd have no trouble with it.

So I ordered one. Turns out there's one more hitch to this flap-mixing deal: the receiver, as shipped in the 4-Site, is in a mode where flap mixing doesn't work. Changing that is a little complicated; this RCGroups thread, How to add Flaps to the E-Flite UM 4-Site using the Dx6i radio, may help.

And Dave was right. With that change, the 4-Site is a pussycat! Very easy to fly, yet very aerobatic. It still sometimes wing-rocks or porpoises when I'm trying to fly straight -- I may need to work on getting the balance just right -- but even then, it's very easy to recover and gives plenty of warning before stalling.

It does want a lot of control throw. The manual that comes with the 4-Site is quite good, but use the "Advanced Pilot" settings even if you're just intermediate. I was nervous about that, but it turned out I wanted as much elevator throw as I could get, and flew all night on high rates.